I recently formatted a USB flash drive on my Mac (El-Capitan) and made a bootable Mojave installer drive. It worked great and there were no issues, until I needed to reformat it to use on Windows again. I've formatted the drive as FAT32 with a MBR partition and it reflects as such in the Disk Utility:

Drive: The screenshot of the drive settings

Partition: The screenshot of the partition settings

Windows Disk Management: The screenshot of Disk Management in Windows 10

CMD Diskpart -> list disk: The screenshot of the disks listed from diskpart.exe

For some reason, Windows doesn't even recognise that the drive is inserted into the PC. I'd expect to see a 16GB disk with no mountable volumes, instead I just see the same disk-listings that were there before I inserted the drive.

What frustrates me is that I've got experience with partitions and it's not usually rocket-science. The third image shows a hybrid drive with a MacOS partition (for my Macbook Air) that also contains a exFat partition for my media.

I've done this before many times over but can't, for the life of me, figure out why it's not working on this flash drive. Have I missed something really obvious? Am I losing my mind?

  • Did you try another USB port on your windows machine?
    – user136834
    Commented Jan 22, 2019 at 15:07
  • @howdytom Yes, I've tried on both front and rear ports on that particular machine as well as my NUC running Windows 7. In fact I had tried on the Win 7 NUC first and just assumed it was Windows acting up!
    – Daniel
    Commented Jan 23, 2019 at 13:05
  • 1
    Try formating your USB flash drive again as HFS+ volume, first. Afterwards reformat it as FAT32. Do you see those issues with different USB drives as well?
    – user136834
    Commented Jan 23, 2019 at 16:39
  • @howdytom thanks, I'm trying that now. I've been using Mac & Windows for 5 years now and this is the first time I've encountered that issue
    – Daniel
    Commented Jan 29, 2019 at 8:55
  • @howdytom your suggestion is confirmed as working. Please load it as an answer and I'll gladly accept it. Thanks so much for this suggestion!
    – Daniel
    Commented Jan 29, 2019 at 10:58

1 Answer 1


Try formating your USB flash drive again as HFS+ volume, first. Afterwards reformat it as FAT32.

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